The present invention relates to an occupant protecting device and an air bag device for a rear-end collision used for protecting an occupant in a back seat of a vehicle from an impact applied to a rear portion of the vehicle.
An air bag device is disclosed in Japanese Laid-Open Utility Model Publication No. 6-65117. The air bag device of the publication includes a sensor for detecting the acceleration applied to a rearmost seat of a vehicle and an air bag accommodated inside the rearmost seat in a folded state. When the sensor detects an acceleration exerted rearward of the vehicle, the air bag is instantly deployed to absorb impact on an occupant seated in the rearmost seat.
Air bag devices have also been proposed other than the air bag device that is mentioned above. In Japanese Laid-Open Utility Model Publication 64-7054, the air bag device that is deployed as described above is accommodated below a trunk, which is located at the rear of the rearmost seat. In Japanese Laid-Open Patent Publication No. 7-186870, the air bag device that is deployed as described above is accommodated below a rear package tray, which its located at the rear of the rearmost seat.
In the air bag device of the above publication No. 6-65117, since a relatively bulky air bag is accommodated inside the seat, the seat becomes less comfortable. In the air bag devices of the publications No. 64-7054 and No. 7-186870, it is required that, to avoid hindering deployment of the air bag, baggage must not be placed in the trunk or on the rear package tray. This reduces convenience.
The air bag devices disclosed in the above publications are formed without considering the predicted movement of the occupant at the collision of the vehicle. For example, when a severe impact is applied to the rear of the vehicle, the occupant seated in the rearmost seat might move rearward along the backrest of the seat. However, the air bag devices are not formed predicting such cases. Thus, the rearward movement of the occupant cannot be prevented sufficiently. When vehicles collide in a state offset in the left or right direction from the traveling direction, the occupant moves in the left or right direction and might hit a rear pillar in the passenger compartment. Depending on the condition of collision, the occupants in the rearmost seat might collide against each other.
In addition, in the air bag devices of the above publications, if the air bag is deployed between the rearmost seat and the rear window glass when, for example, the occupant's head is displaced rearward from the headrest of the rearmost seat, the air bag interferes with the occupant's head. Thus, the air bag is hindered from being deployed in a proper manner.
In an air bag device disclosed in Japanese Laid-Open Patent Publication No. 5-85290, an air bag is accommodated in a rear ceiling of a vehicle in a folded state. When an impact is applied from the rear of the vehicle, inflation gas is supplied to the air bag from an inflator so that the air bag is deployed between the rearmost seat and the rear window glass. However, the air bag only rounds out in the vicinity of the ceiling. Thus, the impact applied to the occupant seated in the rearmost seat is not sufficiently absorbed.
To solve the above problem, a large air bag may be used and the amount of the inflation gas supplied from the inflator may be increased to inflate the air bag in a large size. However, in this case, a large inflator needs to be used, which increases cost of the air bag device.